Recorder apparatus for rapid photographic developing



i 21, 1954 c. F. ROBINSON ETAL 3,130,000

RECORDER APPARATUS FOR RAPID PHOTOGRAPHIC DEVELOPING Original Filed Sept. 5, 195'? m I f mvsmoxs CHARLES E ROBINSON 1 JOHN H. JACOBS ATTORNEYS United States Patent Oflice 3,130,000 Patented Apr. 21, 1964 3,130,000 RECORDER APPARATUS FOR RAPID PHOTOGRAPHIC DEVELOPING Charles F. Robinson, Pasadena, and John H. Jacobs,

Altadena, Callfi, assignors to Consolidated Electrodynamics Corporation, Pasadena, Calif., a corporation of California Original application Sept. 3, 1957, Ser. No. 681,804. Divided and this application Aug. 1, 1961, Ser. No.

5 Claims. (Cl. 346-109) This invention relates to a high speed process for developing photosensitive emulsions and has great utility for rapid access photographic recording. Because of this utility the invention is particularly described in its application to this field although in no sense so limited.

This application is a division of our application Serial No. 681,804, filed September 3, 1957, now abandoned.

As dynamic recording has increased in application and importance, there have evolved fields of use in which a very short access time is desirable. The term access time is used to indicate the time interval between the exposure of a photosensitive recording paper to a light stimulus to be recorded and the presentation of the resultant record for visual observation. The terms photographic paper and recording paper are used throughout the specification and claims to include photosensitive emulsions disposed in any suitable support such as paper, film or other usable medium.

Wind tunnel and flight testing represent examples of testing procedures wherein rapid access is of considerable value. Conditions of operation can be changed with greater facility and flexibility of the conditions undergoing test can be recorded and visually observed in a brief rather than a prolonged interval of time.

Previously conventional photographic recording techniques generally referred to as oscillography have involved the exposure of an entire roll of a record paper to the information to be recorded with subsequent and separate chemical development of the roll thus exposed. In this procedure a record roll of say approximately 250-400 feet in length is entirely exposed before its removal from the oscillographic recorder and its subsequent development by presently conventional means. This procedure thus represents a rather prolonged access time of minutes or even hours.

We have now devised fundamental modifications in the usual developing techniques permitting development of the latent image produced by exposure of a photosensitive medium within a very brief interval subsequent to exposure and even more importantly continuously and concurrently with exposure of succeeding increments of the mediums. By our technique we are able to produce for visual observation a photographic record of excellent resolution and contrast with an access time of approximately one second providing the record transport is maintained at a rate suificient for the medium to emerge from the process in this interval. By way of explanation, it takes a finite space in which to carry out the process and the access time is. dependent then not only on the potential speed of the process but also on the record transport speed through this finite space. In other words, at very low recording speeds, paper travel and not our developing technique becomes the limiting factor in access time.

Basically the invention comprises in one aspect a process for developing a photographic material having a photosensitive emulsion supported on a backing preferably of paper. The method comprises an initial step of applying a thin film of processing solution to the emulsion surface. The applied film of processing solution is carefully controlled to be sufficiently thin so as to wet substantially only the emulsion leaving the emulsion support essentially dry. Immediately after application of the processing solution, heat is applied to the emulsion through the back dry surface of the support to accelerate development of the exposed emulsion and simultaneous drying of the processing solution from the emulsion.

The term processing solution is used throughout specification and claims to designate primarily a developing solution but which for this purpose may include various additives such as emulsion stabilizers and the like. A processing solution particularly applicable to this process is described and claimed in application, Serial No. 669,601, filed by John H. Jacobs on November 29, 1957 (now abandoned), and is discussed in some detail later in this specification.

We have further found that the developing procedures generally outlined above can be carried on substantially simultaneously with the exposure of the recording medium to the light beams to be recorded. In fact, the processing solution may be applied as a thin film directly after such exposure or even prior thereto, but it is desirable that exposure precede the application of heat as described.

An essential limitation to the success of the described process is the application to the recording paper of a thin film only of the processing solution as contrasted to previously conventional procedures of dipping or spraying the record so as to saturate both the emulsion and the paper with developer solution. By limiting the thickness of the applied film such that substantially only the emulsion is moistened, this film being not in excess of .0005 inch and preferably in the neighborhood of .0002 to .0003 inch thick, not only is drying facilitated but the record by reason of its dry back surface may be immediately passed over a stationary hot platen with a minimum of distortion or wrinkling thereof which could impair heat transfer from the platen into the record. Since it is necessary that the record be substantially dry before exposure to ambient light conditions for visual observation, the importance of the thin film principle in permitting very rapid drying speed is obvious. Moreover the application of heat to accelerate drying of the film has the additional advantageous effect of causing changes in the developer so that residual developer remaining in the paper is rendered relatively inert.

As a consequence of all of the factors mentioned above development is not only more rapid than any presently known process, but a comparatively stable developed record is obtained. The resultant record is comparatively stable to light but may show instability only in the presence of excess moisture.

As mentioned above, one of the advantages of the thin film technique is that we are enabled to dry the record by passing it over a stationary platen since the dry backing material slides freely and in this connection one form of apparatus of the invention capable of carrying out the process described above is illustrated in schematic elevation in the accompanying figure.

Referring to the drawing the record handling unit is enclosed in a magazine 10 having on one side a window 11 through which a light beam 12 produced in a conventional recording camera enters the magazine incident on the record therein. The camera is illustrated schematically as a light source 13 and a modulator 14 represented as a galvanorneter mirror. The camera as such forms no part of the present invention and is conventional in the process of oscillography. In the usual commercially employed oscillograph a number of channels of data may be recorded at the same time by the expedient of using a plurality of light modulators and recording the modulations responsive to separate signals applied to the respective modulators and representing a plurality of parameters to be recorded.

Typically, for example, a plurality of pressure transducers may be incorporated in various locations of a w nd tunnel with their outputs separately connected to a dinerent one of a plurality of galvanometers in a multi-channel oscillograph. For the purposes of describing the invention a single galvanometer mirror 14 is shown as illustrative of the phenomena involved with the intention that this be representative of any number of separate channels of recording.

The magazine houses a supply roll 16 on which an unexposed paper 17 is mounted. The record is carried over a metering roller 18 driven by conventional roller drive means (not shown) to determine the speed of travel of the recording medium through the magazine. From the metering roller the record is carried around an idling or tension roller 19 and from thence past a processing solution applicator 20.

The applicator 20 as shown schematically in the drawing comprises a solution reservoir 21, a so-called slit applicator 22 which communicates at one end with the reservoir 21 and at another end bears against the recording medium 17 as it is stretched across a mandrel 23. Within the limits of film thickness specified above any type of solution applicator can be used. Wick-type wipers and slit applicators are satisfactory although simple roller applicators are not because it is a tendency of rollers to apply too thick a layer of fluid. As presently preferred in the practice of this invention we employ a novel slit type applicator which we have found applies an even film of solution without pumping means and which is generally insensitive to variations in record speed. The particular applicator illustrated schematically herein is described in detail and separately claimed in co-pending application, Serial No. 712,148, filed January 30, 1958, by Michael D. Godfrey, now US. Patent No. 2,983,250, issued May 9, 1961.

A further benefit of the thin film technique not heretofore mentioned can be appreciated by reference to the drawing. This additional benefit lies in the many-fold reduction in consumption of processing solution over that occurring in conventional developing procedures. We have noted that an entire roll of conventional photographic recording paper amounting to approximately 400 square feet can be processed with no more than 400 cubic centimeters of processing solution. The same roll processed by conventional procedure of paper dipping would not only take about 10 to 100 times the access time as emphasized above, but would involve the consumption of approximately 900 cubic centimeters of solution. A still further advantage of thin-film application of developing solution is that the developer in supply reservoir 21 remains always at full strength, there being no gradual exhaustion of developer in the process of developing a roll of paper as would be the case if the paper were immersed in the developer. At slower record speeds development is rendered self limiting by reason of rapid drying of the thin film of developer and fogging which would otherwise occur is avoided. In other Words, if a heavy layer of developer were employed the record would fog at low transport speeds because of the excessive time required to render such a heavy application inactive.

The latent image produced in the recording medium at the instant of exposure through window 11 would not be rapidly developed after application with the processing solution at the applicator 22 without further impetus. However, at this point, the record cannot be exposed to ambient light since the emulsion is highly active while it is damp with developer. Accordingly the crux of the rapid access achieved with this process is the ability as above mentioned to apply large quantities of heat relative to the amount of developer present to induce rapid development and simultaneous drying of the extremely thin film of developer at a rapid rate. This is made possible not only because a small volume of developer is involved, but because the recording paper itself has not been wet.

For this purpose the record is carried from the applicator 20 on a guide roller 24 and across a curved face 25 of a heated platen 26. The dimensions of the platen are selected to achieve the desired degree of drying at the ranges of paper speed to be encountered and under acceptable conditions of temperature. Generally speaking we have found that the record can be dried at a temperature in excess of about C. and preferably in the neighborhood of C., requiring a drying time of approximately 0.4 second. This means that with a platen face of about 12 inches :1 paper speed of approximately 25 to 40 inches per second is permissible.

The platen 26 may be heated in conventional fashion by insert heaters (not shown). To accomplish the rapid drying desired it is necessary to transfer relatively large quantities of heat to the record. This can be accomplished by high power input to the platen or more economically can be accomplished by causing the platen to act as a heat sink storing relatively large amounts of heat developed at comparatively low power consumption during periods of inactivity, i.e., while the record roll is being changed. Any form of heated platen may be employed, there being many such adequate to apply the necessary heat to the record.

From the platen the record is passed through com-' pression rolls 27, 28, the roller 27 being driven through a slip clutch to maintain a constant tension on the record strip between the metering roll 18 and the point of the compression rollers. Thereupon the record is discharged from the magazine through an exit slit 29.

Using a class of processing solution particularly adapted to this method as more particularly described in the above-mentioned application of John H. Jacobs, the record obtained from the magazine is sufficiently stable to permit leisurely visual observation. It is the general experience that a large percentage of the records produced in the testing procedures in which these instruments are employed are of no permanent value, and once observed to evidence the conditions under investigation may be destroyed. As related to this large percentage of total record which is to be destroyed the rapid processing technique which eliminates the more time consuming treatment in stabilizing solutions has not only the advantage of quick access but further eliminates stabilization of records which have no permanent value. At the same time the record is of sufficient permanence that any segments of prolonged or permanent value may be selected and separately processed minutes, hours or days later for ultimate stabilization. At this point the time required to stabilize is of no concern since the record has already been observed and has thus served its immediate purpose.

It should be mentioned, however, that there is nothing in this developing process rendering it incompatible with stabilization of the record. If desired an additional liquid applicator may be employed downstream from the point of heating to apply a film of stabilizer such as hypo solution to the developed and dried record. Such a procedure, however, produces additional handling problems which are not generally justified in view of the facility of later subsequent stabilization of edited portions of the developed record.

The developer for use with this process preferably has special characteristics. In particular, it must not fog the sensitive layer at the high temperatures used for rapid development and drying, and its oxidation products should preferably be colorless. Further, the developer components or their pyrolysis and oxidation products should not react with constituents of the photosensitive layer or its support (for instance, the sensitising dyes to be found in most photographic emulsions) to form markedly colored products. This being so, and bearing in mind the diversity of the constituents which may be used in photographic media, optimum results are achieved by formulation of a particular developer to work with a desired type of photographic recording medium. The further possibility exists of evolving specially a recording medium, with a complementary developing solution, which will use the potentialities of the process to the best advantage.

We have found that a combination of 1-phenyl-3- pyrazolidone (pioneered as Phcnidone by Ilford Ltd.) and chloro-l.4-dihydroxybenzene (also known as chlorquinol and chlor-hydroquinone), in association with conventional preservative, alkali, restrainer and antifoggant make a suitable developing solution, giving a low background fog with many recording papers such as Linograph #483 (Eastman); LinoWrit #1(w) or #2(w) (Du- Pont) or Linatrace #3 (thin) (Grant Photo Products). These recording papers are coated with a silver halide develop-out photosensitive emulsion. The use of a wetting agent may assist the rapid entry of the solution into and through the photosensitive layer, and the subsequent uniform drying on the hot platen. We have found that Teepol (Shell Chemical Co.) is well adapted for this use.

As an example of the type of developing solution in use, the following has been found suitable for many recording papers:

Sodium sulfite (anh.) gm 75 Phcnidone gm 6 Chlor-hydroquinone gm 6 Caustic soda (pellets) gm 18 Benzotriazole gm 6 Potassium bromide gm 3 Teepol (stock solution) ml 20 Water to 1000 ml.

It is desirable to start with water, warmed to about 50 C., to the extent of about 80% of the final volume. When all the components have been added and dissolved, preferably in the order given, the solution is made up to the final volume.

The foregoing is essentially one of the compositions discussed in greater detail in the above-mentioned application of John H. Jacobs.

As a significant example of effectiveness of the described process it may be compared with the operation of a presently available commercial oscillograph. In the present instruments paper transport speeds of 2 to 100 inches-per-second or more are possible but the record is made in a detachable magazine which must be taken from the recorder to a dark room and processed in the usual manner. Under ideal circumstances the record may be available for visual examination within approximately 10-20 minutes after exposure. At the slower recording speeds and with records of approximately 250 feet in length there must be added to this time for visual observation of the initially exposed portions the time consumed in exposing the entire record. Employing the pres-' ent process on the other hand any portion of the record is visible in an interval determined only by the time required to travel from exposure to discharge, this being a function of the length of record in residence between the point of exposure and the outlet window of the magazine and the paper speed involved. At recording speeds in excess of about 25 inches per second an access time of only 0.8 second is realized.

To facilitate an understanding of this unique photographic developing technique it has been described as applied to the field of dynamic recording. It is evident from a familiarity with the widespread efforts now being made to achieve rapid record access that this procedure represents a major advance in this field. At the same time the procedure is in no way limited in its usefulness to recording and the detailed description of such application should not be so construed.

We claim:

1. An oscillographic recorder including a record magazine having a window for receiving a light stimulus to be recorded and a camera associated with the magazine for developing such stimulus, the record magazine comprising a housing, a roll of photographic paper, paper drive means for carrying the paper continuously past the window for exposure to the light stimulus, means operable to apply to the emulsion surface of the paper immediately afer exposure a film of process solution not in excess of about .0005 inch thick, a heated platen having a curved outer face, means for drawing the paper carrying the film across the curved face of the platen with the back surface of the paper in contact therewith, means for maintaining the platen above about C., and means to discharge the paper from the magazine.

2. In an oscillograph for recording the variations with time of a phenomenon, the combination of:

a magazine having an opening through the wall thereof, oscillographic recording medium supply means disposed in said magazine and adapted to hold a supply roll onto which is wound a recording medium consisting of a silver halide type emulsion supported on a backing,

a stationary platen surface disposed in said magazine,

a heat source in the magazine for heating the platen surface to a temperature from about 90 centigrade to about centigrade,

drive means for (a) unwinding the medium from the roll,

(b) passing the unwound medium adjacent the wall opening so that radiations passing through said opening fall on the emulsion of said medium, and

(c) passing the medium over the platen surface so that said surface is separated from the emulsion by the backing, and

processing fluid applicator means disposed in said magazine so as to be in contact with the emulsion at a location between the point of emulsion exposure and the point of backing contact with the platen surface and operable to apply a thin film of processing solution to the emulsion, said film being of a thickness suflicient to wet the emulsion without substantially wetting the backing.

3. In an oscillograph having a light source, light from which falls on a galvanometer and is reflected therefrom as an indication of the variation of a phenomenon with time, the combination of:

an oscillographic recording medium of the type having a backing supporting a silver halide emulsion which is sensitive to the radiations reflected from the galvanometer mirror,

a supply roll onto which said medium is wound,

means for unrolling the medium from the supply roll and exposing the emulsion thereof to said reflected radiations,

means for applying processing liquid to the exposed emulsion in a quantity sufficient to wet the emulsion without substantially wetting the backing,

a platen surface,

means for heating the platen surface to a temperature in excess of about 90 centigrade, and

means for passing the medium, after the application of the processing liquid to the emulsion thereof, over the heated. platen so that the backing contacts the platen surface for a period of at least about 0.4 second.

4. In an oscillograph having a light source, light from which falls onto a galvanometer mirror and is reflected therefrom as an indication of the variation of a phenomenon with time, the combination of:

an oscillographic recording medium of the type having a backing supporting a silver halide emulsion which is sensitive to the radiations reflected from the galvanometer mirror,

a supply roll on to which the medium is wound,

means for applying a film of processing fluid, of a thickness of from about 0.0002 to about 0.0005 inch, to the emulsion, so as to wet the emulsion without substantially wetting the backing,

wetted emulsion dryer means having a stationary platen surface and heater means for heating the platen surface to a temperature in excess of about 90 centigrade, and

roller means for unwinding the medium from the supply roll, exposing the medium emulsion to the re flected radiations, contacting the exposed emulsion with the means for applying processing fluid, and passing the wetted emulsion and backing over the dryer means so that the backing is in contact with the platen surface.

5. Apparatus for processing an exposed photosensitive recording medium of the type having a silver halide emulsion supported on an elongated strip backing comprising applicator means for applying a film of processing solution not in excess of 0.0005 inch thick to the emulsion as the recording medium is drawn past the ap plicator means, this film thickness being such that the backing remains essentially unmoistened,

a stationary platen surface,

means for maintaining the platen surface at a-temperature in excess of about 90 centigrade under conditions of recording medium travel across the platen, and

drive means for pulling the recording medium sequentially past the applicator and across the platen with the paper backing in contact with the platen and at such a speed that the developer film is dried to the point of inactivation by the time the recording medium passes completely over the platen.

References Cited in the file of this patent UNITED STATES PATENTS 1,471,357 Ruben Oct. 23, 1923 1,995,199 Bru'nik Mar. 19, 1935 2,315,452 Pifer Mar. 30, 1943 2,548,573 WampOIe et al Apr. 10, 1951 2,751,814 Dimberger June 26, '1956 2,780,972 Fail-bank Feb. 12, 1957 2,995,995 Bakke et a1 .s Aug. 15, 1961 FOREIGN PATENTS 647,922 Great Britain Dec. 28, 1950 

1. AN OSCILLOGRAPHIC RECORDER INCLUDING A RECORD MAGAZINE HAVING A WINDOW FOR RECEIVING A LIGHT STIMULUS TO BE RECORDED AND A CAMERA ASSOCIATED WITH THE MAGAZINE FOR DEVELOPING SUCH STIMULUS, THE RECORD MAGAZINE COMPRISING A HOUSING, A ROLL OF PHOTOGRAPHIC PAPER, PAPER DRIVE MEANS FOR CARRYING THE PAPER CONTINUOUSLY PAST THE WINDOW FOR EXPOSURE TO THE LIGHT STIMULUS, MEANS OPERABLE TO APPLY TO THE EMULSION SURFACE OF THE PAPER IMMEDIATELY AFTER EXPOSURE A FILM OF PROCESS SOLUTION NOT IN EXCESS OF ABOUT .0005 INCH THICK, A HEATED PLATEN HAVING A CURVED OUTER FACE, MEANS FOR DRAWING THE PAPER CARRYING THE FILM ACROSS THE CURVED FACE OF THE PLATEN WITH THE BACK SURFACE OF THE PAPER IN CONTACT THEREWITH, MEANS FOR MAINTAINING THE PLATEN ABOVE ABOUT 90* C., AND MEANS TO DISCHARGE THE PAPER FROM THE MAGAZINE. 